Hillary Clinton has collected a good number of endorsements from individual labor unions. That has helped to solidify her status as the front-runner for the Democratic presidential nomination.

But Clinton will not soon collect the endorsement of the AFL-CIO, the labor federation with which the majority of the nation’s unions are affiliated. And that, say backers of Vermont Senator Bernie Sanders, opens the way for grassroots labor activists to step up their campaigning for the insurgent challenger.

For months, there was speculation about whether the AFL-CIO executive council might make an endorsement at its February 21–24 winter meeting in San Diego

But AFL-CIO President Richard Trumka ended the speculation Wednesday.

“Our Executive Council will discuss the 2016 election cycle during its Winter Meeting, but no presidential endorsement will be made,” Trumka wrote in an e-mail distributed to executive council members in advance of San Diego meeting. “From the very start of the presidential contest, we have been clear that we have an endorsement process in place, and that we will continue to follow that process in accordance with our Constitution.”

According to a Huffington Post report, Trumka explained to the executive council members that, “Following recent discussion at the AFL-CIO’s Executive Committee meeting and subsequent conversations with many of you, I have concluded that there is broad consensus for the AFL-CIO to remain neutral in the presidential primaries for the time being and refrain from endorsing any candidate at this moment.”

The decision comes as Clinton and Sanders are campaigning aggressively for the support of union members in Nevada, where Democrats will caucus on Saturday, and in a host of labor strongholds that will soon hold caucuses and primaries. And Sanders backers welcomed it as a boost for the Vermont senator, who beat Clinton in the New Hampshire primary and whose poll numbers have spiked in recent weeks. Former Communications Workers of America union president Larry Cohen, a key Sanders backer, says the neutral stance by the AFL-CIO “means that union members and other working Americans are not going to be facing a coordinated campaign from the AFL-CIO for the other candidate.”

When the 2016 race was getting started, the prospect of an early endorsement of Clinton by the labor federation was taken seriously by all sides.

Though Sanders has long been allied with labor, and though he has been a ardent foe of the Trans-Pacific Partnership trade agreement that unions passionately oppose, he did not automatically secure union endorsements. Clinton reached out early to union leaders, many of whom had known and worked with her for years. In addition, the former secretary of state’s initial polling and fundraising advantages gave her an upper hand in the pursuit of coveted endorsements.

Clinton has over the course of the campaign picked up almost two dozen endorsements from major unions, including the National Education Association, the American Federation of Teachers, the American Federation of State, County and Municipal Employees, the Service Employees International Union, the International Federation of Machinists and the Laborers International Union of North America. Among the unions backing Clinton are several with highly effective political operations, including the International Union of Painters and Allied Trades, which announced its endorsement with a declaration that its members “are ready to work every day to elect Hillary Clinton as our next President of the United States.”

Clinton’s labor backers are regularly featured at her rallies and labor volunteers have played an important role in her campaign’s voter mobilization efforts in early states.

Yet, labor has not been united for Clinton.

A number of the nation’s largest and most prominent unions, including the United Steelworkers and the United Auto Workers have not endorsed. Nor have the Teamsters. Those three unions have focused intense energy on trade fights in recent months, especially the struggle over the TPP.

At the same time, Sanders has secured important endorsements from a number of activist unions, including National Nurses United, the American Postal Workers Union, and the Communications Workers of America. These unions have poured a energy into supporting the senator, becoming a major presence on the campaign trail in states such as Iowa, New Hampshire, South Carolina and Nevada. Sanders has also gained support from local unions in key states, such as United Steelworkers Local 310 in Iowa, the International Brotherhood of Electrical Workers Local 490 in New Hampshire and the Pennsylvania Association of Staff Nurses and Allied Professionals. A national grassroots coalition, the Labor Campaign for Bernie Sanders, has for months urged local, state and national union groups to back the senator, arguing that: “Labor must step up to change the direction of American politics. We need politics to focus on the issues of our time: growing inequality and pervasive racism, the power of concentrated wealth and its corruption of our democracy, an escalating pension and retirement security crisis, runaway military spending and a militarized foreign policy, Medicare for All, and the need for new, bold solutions to our shared problems.”

A petition drive organized by California labor activist Nicholas Gerry collected almost 40,000 signatures urging the AFL-CIO to back Sanders.

An actual AFL-CIO endorsement of Sanders was always going to be as a tall order. Sanders backers within the federation knew that, so for many of them the focus was on keeping the AFL-CIO neutral. Though Gerry expressed disappointment that the federation did not back Sanders, in a message posted following the distribution of Trumka’s e-mail he explained that “this is still a win for us as at the very least all the resources of the AFL-CIO won’t be towards the wrong candidate.”

With Trumka encouraging affiliated unions “to pursue their own deliberations with their members and come to their own endorsement decisions,” Sanders backer Larry Cohen said, “It’s a green light for people to do what moves them, and that’s what democracy looks like.”